Carbonless manifold business forms

ABSTRACT

Sets of manifold business forms are coated on selected surfaces thereof with chemicals which are capable of reacting with each other to produce a colored mark. In one arrangement at least one intermediate sheet is coated on one surface with a composition of a record-developing material (which is generally solid) and a non-compatible color precursor (which is generally in the form of a microencapsulated liquid) to thereby function as both a record-receiving and a color-transfer surface upon reacting with the coating of at least another separate sheet of the set containing another compatible color precursor and/or another record-developing material on the surface thereof. In another arrangement, some of the sheets are coated front and back with a record-developing material, while others are coated front and back with a microencapsulated color precursor. In each of the arrangements the sheets of the manifolded sets are capable of being so arranged such that by removal of certain parts of the sets or turning certain parts upside down and applying pressure on the backs of the sets, images may be developed on both sides of the sheets.

BACKGROUND OF THE INVENTION:

1. Field of the Invention:

The present invention relates generally to a carbonless copying systemwherein mating sheet surfaces are coated respectively with compatibleinitially colorless reactive components capable of reacting to produce acolored mark upon impact. More particularly, the invention relates tomanifold sets utilizing both single and dual initially colorless colorforming systems whereby it is possible to produce a colored mark on bothsides of such sheets by impact.

2. Description of the Prior Art:

Manifolded sets of carbonless copying paper normally comprise a topsheet, a bottom sheet and at least one intermediate sheet disposedtherebetween. The top sheet which is conventionally coated on its backsurface with an encapsulated solution of a colorless color-former in asuitable solvent and is generally therefore referred to as CB ("CoatedBack") paper. The bottom sheet conventionally has its front surfacecoated with a solid material containing a record-developing material andthis "front coated" sheet is generally referred to as CF paper. Theintermediate sheets are often coated respectively with theabove-mentioned solid record-developing material in the front coatingsand with the color precursor in the back coatings and accordingly such"front and back coated" sheets are referred to as CFB paper. The backcoatings normally comprise pressure rupturable microcapsules containinga fluid color precursor in fluid form which is capable of reacting tothereby form a colored compound with the developing material in thefront coating of the next adjacent sheet so that, upon impact by amachine key or application of pressure by a stylus on the top sheet, thecontents of the ruptured capsules in the back coatings spill out andreact with the developing material to form a colored mark on the latterwhich corresponds to the mark impressed by the stylus or machine key.

The present invention relates generally to a co-pending and commonlyowned U.S. application Ser. No. 466,910, filed May 3, 1974, and entitled"DUAL SYSTEM CARBONLESS PAPER", now abandoned the entirety of thedisclosure of which is hereby specifically incorporated herein byreference. In this regard it is to be noted that the present applicationalso relates to dual systems of co-reactive materials; however, thepresent invention differs from that of the above-mentioned applicationin its construction and purpose as will be more clearly brought outhereinafter.

Although, in conventional manifolded carbonless copying sets, the backcoatings normally comprise a microencapsulated solution of the colorprecursor and the front coatings normally comprise a solidrecord-developing material, it should be pointed out that the reverse isalso possible so that the front coatings comprise microcapsules and theback coatings comprise a solid record-developing material. Moreover, theco-reactants may both be microencapsulated liquids. United Statespatents which illustrate various types of systems which may be used inthe production of carbonless transfer papers are, for example, U.S. PatNo. 2,299,694 to Green, U.S. Pat. No. 2,712,507 to Green, U.S. Pat. No.3,016,308 to Macaulay, U.S. Pat. No. 3,429,827 to Ruus and U.S. Pat. No.3,720,534 to Macaulay et al.

The aforementioned Green ('507) and Macaulay ('308) patents illustratethe most common variety of carbonless impact transfer paper of the typewith which the present invention is primarily concerned whereinmicrocapsules containing a liquid fill comprising a chemically reactivecolor-forming precursor are coated on the back surface of a sheet, and adry coating of a solid coreactant chemical for the precursor is coatedon the front surface of a receiving sheet.

In the current carbonless copying systems of the type aforedescribed theimage is usually developed on the front sides of the sheets. In certaincases, however, it is desirable and advantageous for images to beproduced on both sides of several or all sheets of a set of manifoldbusiness forms. Depending on the particular business needs, varioustypes of entries are required to be made on the sheets of a manifoldedset of forms thereby requiring larger and more detailed sets of forms tobe made which results in the need for more paper and precise printingtechniques. Carbon transfer sheets have sometimes therefore beeninterleaved with carbonless paper systems so that, after an image isproduced on the front side of the receiving sheet using the carbonlesssystem, an image can also be produced on the back side of such receivingsheet by means of the conventional carbon transfer. The problems ofcarbon smudging, poor manifolding and difficulty in manufacturenevertheless persist in such an arrangement.

An interesting prior reference is Japanese patent publication No.43-28652. This patent discloses a carbonless duplicating notebookconsisting of a set of initially colorless copying sheets containingpressure rupturable components for transfer of the color formingingredients. The patent is basically directed to a base sheet having afirst color forming reactant on each side thereof. A plurality ofsecondary sheets are provided each of which has one side thereof coatedwith a second color forming reactant reactable with the first colorforming reactant to form a color and the second side thereof coated withthe first color forming reactant. Sets are formed by placing thesecondary sheets on either side of the base film with the second colorforming reactant coated surfaces facing the first color forming reactantsurfaces. However, this patent does not generally disclose the conceptof having an image produced on each side of the sheets of the set.

SUMMARY OF THE INVENTION:

It is therefore an object of the present invention to provide acompletely carbonless manifolded set of recording sheets so constructedto permit an image to be developed on both sides of the sheets.

Another object of this invention is to provide such a manifolded setwherein individual sheets may be coated with a mixture of amicroencapsulated color precursor and a record-developing material whichis non-compatible therewith. By itself such a coating cannot present aso-called self-contained sheet since image development cannot occur ifsuch capsule contents and the record-developing material come intocontact. However, such sheet can act both as a record-receiving CF sheetand as a color-transfer surface CB sheet. Image development may then beprovided by using separate sheets coated with a compatible colorprecursor or record-developing material.

A further object is to provide a manifolded set wherein each sheet iscoated both front and back with a record-developing material and/or witha microencapsulated color precursor.

A still further object of the present invention is to provide such amanifolded set wherein a chemically compatible reaction system isemployed using color precursors and record-developing coatings disposedon selected surfaces of the sheets to facilitate development of an imageon both sides of the sheets.

A still further object is to provide a manifolded set wherein tworeaction systems are employed such that the color precursor of onesystem is chemically incompatible to develop a color with therecord-developing material of the other, and vice versa, although thevarious components of both systems may be coated on selected surfaces ofthe sheets and/or as a mixture on selected surfaces so as to facilitatea wide range of manifolded transfer paper sets capable of producingimages on both sides of the sheets.

Other objects, advantages and novel features of the invention willbecome more apparent from the following detailed description of theinvention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

FIGS. 1 through 4 are elevational, expanded and enlarged,cross-sectional views of several embodiments of manifolded sets ofcarbonless recording sheets embodying the principles and concepts of thepresent invention; and

FIGS. 1A through 4A are views similar to FIGS. 1 to 4, respectively,showing the arrangement of the sheets for each embodiment to facilitateimage development on the opposite sides thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS:

The manifolded set of carbonless recording sheets generally designatedby the reference numeral 10 in FIG. 1 includes a top sheet 11, a bottomsheet 12 and several intermediate sheets 13 through 17. The top andbottom sheets 11 and 12 are respectively coated back and front withcoatings 180 and 190, while intermediate sheets 13, 15 and 17 includeback coatings 210. Intermediate sheets 14 and 16 each include frontcoatings 190 and back coatings 180. As shown, each of the sheets 11through 17 are disposed to overlie one another with their back coatingsand front coatings therethroughout normally in contact with one anotherin the manifolded set, although these sheets are shown as beingvertically spaced in FIG. 1 for the sake of clarity. Each of thecoatings 180, 190 and 210 includes at least one color-forming reactivematerial, and the reactive material in each of the back coatings 210 iscapable of reacting with a reactive material in each of the frontcoatings 190, when pressed thereagainst, to produce a colored mark in amanner to be more fully described hereinafter. The reactive material ineach coating 180 is capable of reacting with a reactive material in eachof the coatings 190 when arranged as shown in FIG. 1A for contacttherewith, in a manner to be hereinafter more fully described. However,the reactive materials in coatings 180 and 210 are chemicallyincompatible to form a color.

Although five intermediate sheets are shown in FIG. 1, it should bepointed out that set 10 could include additional intermediate sheetssimilar to 14 or 16 and 13, 15 or 17, and could likewise include as fewsheets as 11, 13 and 12 without departing from the principles andconcepts of the present invention.

The reactive material in each coating 210 comprises a first initiallycolorless reactive component of a first initially colorless reactionsystem. The reactive material in each coating 190 comprises a mixture ofa second initially colorless reactive component of the first reactionsystem and a first initially colorless reactive component of a secondreaction system. Further, the reactive material in each coating 180comprises a second initially colorless reactive component of the secondreaction system. The first and second components of the first system arecapable of interreacting when brought into reactive contact with oneanother, such as by impact, to produce a colored mark. Likewise, thefirst and second reactive components of the second system are capable ofinterreacting when brought into reactive contact with one another toproduce a similar colored mark. On the other hand, the second reactivecomponent of the second reactive system in coatings 180 is notchemically compatible to produce a colored mark when brought intocontact with the first reactive component of the first reactive systemin coatings 210. Further, the second component of the first reactivesystem and the first reactive component of the second reactive system incoatings 190 are not chemically compatible to form a colored mark.

Generally the reactive components of coatings 210 will be identical.However, it should be pointed out, that the use of a third reactionsystem is possible in that the reactive material in coating 210 of sheet17 might be chemically compatible only with a reactive component of themixture of components in the coating 190 of sheet 12, and notcompatible, for example, with a reactive component of the mixture ofcomponents in coating 190 of intermediate sheets 14 and/or 16.Similarly, sets including more than three different color systems couldbe utilized in connection with the present invention.

FIG. 1 illustrates the manner in which images are transferred onto asurface of several sheets underlying top sheet 11 as pressure is appliedthereto in the direction of arrow 70. Preferably, at least one of themixture of components in coatings 190 is contained in the form of aliquid fill material in tiny rupturable microscopic capsules. This fillcomprises the first reactive component of the second reactive systemdescribed above. The tiny rupturable mircocapsules are illustrated assmall circles. Likewise, coatings 210 preferably comprise tinyrupturable microscopic capsules having liquid fill therein, which fillcomprises the first reactive component of the first reactive system.Such microcapsules are also illustrated by small circles. When thecapsules in coatings 210 are ruptured, by the application of pressure bystylus or machine key to the upper surface of sheet 11, as indicated bythe arrow 70 in FIG. 1, a mark 24 may immediately be impressed on topsheet 11 of the set and corresponding marks 25 are formed on the uppersurfaces of sheets 14, 16 and 12 as the fill from coatings 210 of sheets13, 15 and 17 spills out of these ruptured capsules to contact andco-react with the second reactive component of the first reaction systemcontained in the mixture of reactive components of coatings 190 ofcorresponding underlying sheets 13, 15 and 17. Obviously, since the topsurfaces of intermediate sheets 13, 15 and 17 are uncoated, no mark isleft on these surfaces.

Throughout the drawings, the encapsulated first reactive component ofthe first reactive system is illustrated as a series of small circlescontaining a plus mark + while the first reactive component of thesecond reactive system is illustrated as a series of small circlescontaining an x mark x. The second reactive component of the firstreaction system is illustrated as a series of plus marks (+), while thesecond reactive component of the second reaction system is illustratedas a series of x marks (x).

For producing images on the opposite surfaces of sheets 14, 16 and 12which have been marked, as described above, sheets 13, 15 and 17 areremoved and the set is turned over to form a set 10A illustrated in FIG.1A wherein sheet 12, which was previously the bottom sheet, is now thetop sheet for receiving an impact as illustrated by the arrow 71 in FIG.1A. Now, coatings 180 containing the second reactive component of thesecond reactive system respectively underlie and are in contact withcoatings 190 of sheets 12, 16 and 14 which include the first reactivecomponent of the second reaction system. Upon impact by a stylus ormachine key in the direction of arrow 71 as shown in FIG. 1A, a mark 26is immediately impressed on the surface of sheet 12 and the capsulescontaining a first reactive component of the second reactive system areruptured so that the liquid fill thereof spills out to contact andco-react with the second reactive component of the second reactivesystem contained in corresponding coatings 180. Therefore, images ormarks 27 are produced on the coatings 180 of the correspondingunderlying sheets 16, 14 and 11. Sheet 12 of set 10A therefore has marks25 and 26 on opposite sides thereof, each sheet 14 and 16 has marks 25and 27 on opposite sides thereof and sheet 11 has marks 24 and 27 on itsopposite sides.

In FIG. 2, manifold set 20 comprises a top sheet 28, a bottom sheet 31and an intermediate sheet 29. The top sheet is coated on its front andon its back with coatings 21a and 21b, each of which contains the firstreactive component of the first reactive system. Bottom sheet 31 hascoatings 78a and 78b on its opposite sides, each of which contains thesecond reactive component of the second reactive system. Intermediatesheet 29 carries coatings 19a and 19b on its respective opposite sides.Each coatings 19a and 19b comprises an admixture of the second reactivecomponent of the first system and the first reactive component of thesecond reactive system, which components are not chemically compatibleto react to produce a color. The pressure of a stylus or machine keyimpressed on the top surface of sheet 28 in the direction of arrow 72immediately imprints a mark 32, the image of which is transferred ontothe top surfaces of underlying sheets 29 and 31 as markings 33. Thesheets of set 20, similarly, as in the earlier described embodiment, areactually in face-to-face contact, and the fill comprising the firstcomponent of the first system which is contained within themicrocapsules of coating 21b is spilled from the ruptured capsules uponimpact by the key or stylus so as to contact and co-react with thesecond reactive component of the first reaction system in the uppercoating 19a of sheet 29. Likewise, the microcapsules which contain thefirst reactive component of the second reactive system and which areadmixed in the coating layer 19b on the lower surface of sheet 29 areruptured upon impact by the key or stylus so that the fill containedtherein spills out to contact and co-react with the reactive materialcomprising the second component of the second system in upper coating78A of bottom sheet 31.

For producing images on the reverse sides of the sheets, each sheet 28,29 and 31 is turned upside down to present the set 20A of FIG. 2A. Amark 34 is then impressed directly upon the now upper layer 21b of theform by a stylus or machine key applying pressure in the direction ofthe arrow 73. An image 35 of the mark is created on surface 19b of sheet29 as the first reactive component of the first reaction system ofcoating 21a spills from the ruptured mircocapsules to contact andco-react with the second reactive component of the first reaction systemin coating 19b. As before, microcapsules in coating 19a are rupturedupon impact, and the contents thereof comprising the first component ofthe second system spills out to contact and co-react with the chemicallycompatible second component of the second system in coating 78b of sheet31 thereby forming another mark 35. Accordingly, sheet 28 has marks 32and 34 on opposite surfaces thereof while sheets 29 and 31 have markings33 and 35 on opposite surfaces thereof.

In the FIG. 3 embodiment, a manifolded set 30 of carbonless paper sheetsis shown as comprising a top sheet 36, a bottom sheet 37 andintermediate sheets 38 through 43 lying therebetween. Again, each of thesheets are in face-to-face contact with one another; however, the sameare shown as being spaced for improved clarity. Here, sheet 36 has aback coating 18a, sheet 37 has a front coating 18b, sheet 39 hascoatings 18c and 18d on opposite sides thereof, and sheet 42 hascoatings 18e and 18f on opposite sides thereof. Each of the coatings 18athrough 18f comprise the second reactive component of the first reactionsystem. Intermediate sheets 38, 41 and 43 respectively have backcoatings 44a, 44b and 44c thereon comprising microcapsules containingthe first reactive component of the first reaction system. Therefore,upon impact by a stylus or machine key in the direction of the arrow 74,a mark 45 is impressed on the upper surface of sheet 36, microcapsulescontaining the reactive component in coating 44a are ruptured andco-react with the reactive component in coating 18c whereby the reactivecomponent spills out to contact therewith. Likewise, the reactivecomponents from coatings 44b and 44c react with the reactive componentsin layers 18e and 18b respectively. Images 46 of the mark are therebyproduced on each of sheets 39, 42 and 37. Since the top surfaces ofsheets 38, 41 and 43 are uncoated, no image is transferred onto thesesurfaces. It should be appreciated that the sheets of set 30 in FIG. 3have been described as containing the co-reactants of the first systemonly; however, they could similarly be likewise coated in a similarmanner with the co-reactants of another initially colorless colorforming system. Moreover, additional intermediate sheets constructed inthe same manner as sheets 42 and 43 could be used with this set, and, asfew as three sheets, such as, for example, sheets 36, 38 and 37 could beused without departing from the teachings of the invention shown by thisembodiment.

To facilitate a transfer of images on the reverse sides of the markedsheets of FIG. 3, sheets 38, 41 and 43 are first turned upside down andthereafter the entire manifolded set is likewise turned upside down topresent set 30A useful for marking the reverse sides of sheets 37, 42,39 and 36 as shown in FIG. 3A. Here, upon impact with what is now theupper surface of sheet 37 by means of a stylus or machine key in thedirection of arrow 75, a mark 47 is immediately impressed upon sheet 37and images 48 thereof are transferred to sheets 42, 39 and 36respectively as the microcapsules in coatings 44c, 44b 44a are rupturedwhereby the fill thereof spills out to contact and react with theco-reactive components in the respective underlying coatings 18f, 18dand 18a. As a result, sheet 37 has marks 46 and 47 on its opposite sideswhile the opposite sides of sheet 36 have marks 45 and 48 thereon. Eachof the intermediate sheets 42 and 39 has marks 46 and 48 on its oppositesurfaces.

Manifolded set 40 shown in FIG. 4 makes use of only a single system ofco-reactants. Top sheet 49 has coatings 44d and 44e on its oppositesurfaces comprising capsules containing the first reactive component ofthe reaction system while bottom sheet 51 has coatings 18g and 18h onits opposite surfaces comprising the second reactive component of thereaction system. A mark 52 may be impressed upon the surface of layer44d of sheet 49 by means of a stylus or machine key moving in thedirection of the arrow 76, and such mark is imaged as mark 53 on the topsurface of sheet 51 as the microcapsules in coating 44e rupture and thefill thereof spills out to contact and co-react with the co-reactivecomponent in coating 18g of sheet 51.

Sheets 49 and 51 are then separately turned upside down so that coating44d and 18h are facing one another to thereby present set 40A asillustrated in FIG. 4A, to facilitate the production of markings on theopposite sides of the sheets 49 and 51. The co-reactants in thecontacting coatings 44d and 18h of the sheets co-react to produce animage 55 on sheet 51 as a mark 54 is impressed on sheet 49 by a stylusor machine key applying pressure in the direction of the arrow 77.Again, the microcapsules in coating 44d rupture so that the fillcontained therein spills out to contact and co-react with theco-reactive material in coating 18h.

It should be pointed out that in each of the embodiments wherein one ormore sheets or sets are turned upside down, the turning takes placeabout an axis perpendicular to the plane of the drawings.

The precursors useful in connection with carbonless copying systems arevaried and known to those having ordinary skiill in this art. As anexample, particular reference is made to the color precursors mentionedin U.S. Pat. No. 3,455,721 to Phillips, Jr. et al, and particularly tothose listed in the paragraph bridging columns 5 and 6 thereof. Thesematerials are capable of reacting with a CF coating containing an acidicmaterial such as the acid-leached bentonite-type clay disclosed in acommonly owned U.S. Application of Baxter, Ser. No. 125,075, filed Mar.17, 1971 (the entirety of which is hereby specifically incorporated byreference), or the acid-reactant organic polymeric material disclosed inthe Phillips, Jr., et al '721 patent. It should be pointed out also thatthere are a great number of patents which relate to initially colorlesscolor precursors useful in connection with carbonless copying systems.The present invention in no way depends on the exact identity or natureof the reactants utilized except that at least one system ofco-reactants is required for two of the presently disclosed embodiments,and that at least two non-compatible systems of co-reactants arerequired for another two of the disclosed embodiments. When a singlesystem is used, the two co-reactants are of course chemically compatibleto produce a color. Where two systems are utilized, the first reactivecomponent of the first reaction system must be chemically incapable ofreacting with the second reactive component of the second reactionsystem to produce a color and the first reactive component of the secondreaction system must likewise be chemically incapable of reacting withthe second reactive component of the first reaction system to produce acolor. Manifestly the first and second reactive components of the firstsystem are chemically reactive to form a color and likewise the firstand second reactive components of the second reaction system arechemically reactive to form a color.

For one of these systems, any of the materials disclosed in the '721patent referred to above, which are capable of undergoing an acid-basetype reaction with an acidic material, may be utilized. Also operable inconnection with this first system are the spirodipyran compoundsdisclosed in the U.S. Pat. No. 3,293,060 to Harbort, with specificreference being made to the disclosure of this patent in column 11, line32 through column 12, line 21. Particularly useful color precursors aredisclosed in the patents to Davis, U.S. Pat. Nos. 3,193,404, 3,278,327and 3,377,185. The color precursors of Harbort as well as those ofPhillips, Jr. et al and Davis are initially colorless and are capable ofbecoming highly colored when brought into contact with an acidicmaterial such as an acid activated bentonite clay or an acid-reactingpolymeric material, or the like. The Harbort, Phillips, Jr. et al andDavis disclosures are specifically incorporated herein by reference,although there are any number of similar color precursors capable ofundergoing a reaction with an acidic coating to produce a color whichare usable herewith.

In general, the color precursor materials of the Phillips, Jr. et al,the Harbort and the Davis patents may be dissolved in a solvent and thesolution may be encapsulated as taught in the Macaulay '308 and theGreen '507 patents mentioned hereinabove. Other processes forencapsulating color precursors are disclosed in U.S. Pat. No. 3,429,827to Ruus and in U.S. Pat. No. 3,578,605 to Baxter. In this connection, itshould be pointed out that the exact nature of the capsule itself is notcritical so long as the same is capable of containing the colorprecursor with the capsules capable of being ruptured upon impact inaccordance with the conventional carbonless copying procedures. Solventswhich are useful in connection with dissolving color precursors includechlorinated biphenyls, vegetable oils (castor oil, coconut oil,cottonseed oil, etc.) esters (dibutyl adipate, dibutyl phthalate, butylbenzyl adipate, benzyl octyl adipate, tricresyl phosphate, trioctylphosphate, etc.), petroleum derivatives (petroleum spirits, kerosene,mineral oils, etc.), aromatic solvents (benzene, toluene, etc.) siliconeoils, or any combinations of the foregoing. Particularly useful are thealkylated naphthalene solvents disclosed in U.S. Pat. No. 3,806,463 toKonishi et al.

With regard to the acidic coatings capable of converting the colorprecursors into their highly colored form, particular reference is madeto the clay coatings disclosed by Baxter in application Ser. No. 125,075referred to above.

In each of the above mentioned color-forming systems, it is conventionalfor the color precursors to be contained in pressure rupturablemicrocapsules which are coated on the backs of the sheets of carbonlesscopying manifolded sets. Also, the acidic coatings are normally coatedon the fronts of the sheets with the color precursor material in asolvent therefor being transferred from an adjacent back coating to theacidic layer front coating upon rupture of the adjacent capsules whichcontain the color precursor material.

For examples of a second initially colorless reaction system wherein thereactive components are chemically non-reactive with the acid-base typereactants of the systems, described above, reference is made to thepatents to Ostlie, U.S. Pat. No. 3,481,759, Matson, U.S. Pat. No.3,516,846 and Matson, U.S. Pat. No. 3,516,941. The systems disclosed inthese patents include a dithiooxamide compound as one component and ametal rosinate, particularly nickel rosinate, as the other component. Ingeneral, the dithiooxamide material is incorporated into a suitablesolvent therefor, such as cyclohexane, and is microencapsulated. Therupturable microcapsules containing the dithiooxamide fill material arethen utilized as the back coating in a carbonless copying system. Themetal rosinate salt in used as a front coating and the two materialsreact to present a clear mark. The color systems disclosed in the Ostlie'759 and in the Matson '846 and '941 patents referred to above are quiteuseful in connetion with the present invention in combination with thesystems disclosed in the Phillips, Jr. et al '721, the Harbort '060 andthe Davis '404, '327 and '185 patents in view of the fact that thePhillips, Jr. et al, the Harbort and the Davis color precursors are notreactable with matallic rosinates to form a color and the dithiooxamidesof Ostlie and Matson are not reactable with acidic layers, such as ofacid-leached bentonite-type clay or acidic polymeric materials, forimage development. Other patents which disclose dithiooxamidecolor-forming systems are U.S. Pat. Nos. 3,287,154, 3,437,677 and3,558,341.

Other initially colorless color forming systems which may be useful inconnection with the present invention include an alkali metalgallate-iron lactate salt system as disclosed in U.S. Pat. No.2,870,040; a system wherein an acid ester substituted polyhydric phenolis reacted with an iron or vanadium compound to produce a highly coloredchelated compound as disclosed in U.S. Pat. No. 3,535,139; a systemwherein an organovanadium compound is reacted with an aromatic hydroxycompound as disclosed in U.S. Pat. Nos. 3,592,677 and 3,632,617; systemswherein phloroglucinol, 3-hydroxyphenyl urea, aniline hydrochloride,4-aminophenylglycine hydrochloride, N,N-dimethyl-p-phenylenediaminehydrochloride, 3-aminopyridine, skatole, 3,4-dimethyl-5-pyrazolone,2-methylindole, or cobalt thiocyanate is reacted with lignin to form avisible reaction product as disclosed in U.S. Pat. No. 3,450,553; andsystems wherein an alkali metal or ammonium iodide solution is appliedto a surface containing a color forming iodine-reactive substance and anagent for releasing iodine from the iodine solution, as disclosed inU.S. Pat. No. 3,677,786. Another system which has been found to beoperable in accordance with the present invention in connection with aLewis acid-Lewis base reaction system is a system wherein diphenylcarbazide is reacted with nickel stearate.

With respect to the specific embodiments of the present invention,coatings 210 in FIGS. 1 and 1A, coatings 21a and 21b in FIGS. 2 and 2Aand coatings 44a through 44e in FIGS. 3, 3A, 4 and 4A may includemicrocapsules containing a fill material comprising, as the firstinitially colorless reactive component of a first initially colorlessreaction system, a color precursor selected from among those disclosedin U.S. Pat. Nos. 3,455,721, 3,293,060, 3,193,404, 3,278,327, and3,377,185 discussed above. Coatings 190 of FIGS. 1 and 1A, coatings 19aand 19b of FIGS. 2 and 2A and coatings 18a through 18h of FIGS. 3, 3A, 4and 4A may include, as the second reactive component of such firstreaction system, a color-forming reactive material such as theacid-treated bentonite-type clay disclosed in Baxter's application Ser.No. 125,075 or the acidic polymeric materials disclosed in U.S. Pat. No.3,455,721.

Coatings 190 of FIGS. 1 and 1A and coatings 19a and 19b of FIGS. 2 and2A may also comprise, in admixture with the acidic reactive components,microcapsules containing a liquid fill including, as the first initiallycolorless reactive component of a second initially colorless reactionsystem, a dithiooxamide material of the sort disclosed in U.S. Pat. Nos.3,516,846 and 3,516,941 mentioned above. The second reactive componentof the second reaction system is included in coatings 180 of FIGS. 1 and1A and coatings 78a and 78b of FIGS. 2 and 2A. This component maycomprise, for example, a metallic rosinate salt.

As pointed out earlier, it is critical to the invention that the firstand second components of the first system be chemically compatible forimage development and that the first and second components of the secondsystem be likewise chemically compatible for image development. However,the first component of the first system and the second component of thesecond system must not be capable of reacting to form a color andlikewise, the first component of the second system and the secondcomponent of the first system must not be capable of reacting to form acolor. Other than this, the sole basis for choosing between one oranother of the various chemical reactants disclosed above is the colordesired in the final copy produced by the colorless copying system.

As a specific example of the color forming materials used with thepresent invention, coatings 210, 21a, 21b and 44a through e preferablycomprise an encapsulated solution of p-toluene sulfinate of Michler'shydrol in a suitable solvent therefor. The acidic color forming reactivecomponent of coatings 190, 19a, 19b and 18a through 18h preferablycomprises the acid-treated bentonite-type clay material disclosed byBaxter in application Ser. No. 125,075.

The microcapsules included in coatings 190, 19a and 19b preferablycontain, as the first reactive component of the second reaction system,a dithiooxamide material as described in Example 18 of U.S. Pat. No.3,516,846. This dithiooxamide material is dissolved in an appropriatesolvent as in also described in Example 18 of the '846 patent. Theintended capsule fill material is then microencapsulated and themicrocapsules are coated onto a sheet of paper in accordance withExample 19 of this same patent. Coatings 180, 78a and 78b preferablycomprise nickel rosinate which has been coated on the respective sheetsby forming a solution of nickel rosinate which is applied to the sheetsand the solvents removed by drying to leave the required residue. Thisprocedure is also described generally in Example 18 of said '846 patent.

Coatings 190, 19a and 19b in the FIGS. 1, 1A, 2 and 2A preferablyinclude both the microencapsulated dithiooxamide material describedabove and the acid-treated bentonite-type clay material describedearlier. In the production of coatings 190, 19a and 19b, themicrocapsules may first be applied to the appropriate surface of sheets12, 14 and 16 and to each surface of sheet 29. Thereafter, a slurry ofacid-treated bentonite-type clay, may be applied to this microcapsularcoating and allowed to dry.

In view of the foregoing, it can be seen that a simple and economicalyet highly effective manifolded set of carbonless copying papers is setforth in several embodiments, each of which is capable of having imagesproduced on opposite sides of its sheets.

Obviously, many modifications and variations of the invention are madepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

I claim:
 1. A manifold set of carbonless recording sheets comprising:astack including at least three superimposed sheets; the initiallyuppermost and the middle sheets each having a coating on theirrespective back surfaces and the initially lowermost sheet having acoating on its front surface; the back coating of the middle sheetcomprising, as a reactive component thereof, a first reactive componentof a first initially colorless color forming reaction system, and thefront coating of the initially lowermost sheet comprising, as a reactivecomponent thereof, a second reactive component of said first reactionsystem; the front coating of the initially lowermost sheet alsocomprising, as a reactive component thereof, a first reactive componentof a second initially colorless color forming reaction system and theback coating of the initially uppermost sheet comprising, as a reactivecomponent thereof, a second reactive component of said second reactionsystem, said first and second components of the first reaction systembeing capable of interreacting to produce a colored mark upon cominginto reactive contact, said first and second components of the secondreaction system likewise being capable of interreacting to produce acolored mark upon coming into reactive contact, said first component ofthe first system and said second component of the system being incapableof interreacting to produce a colored mark, said first component of thesecond system and said second component of the first system beingincapable of interreacting to produce a colored mark, said middle sheetbeing initially disposed in overlying relationship to said lowermostsheet such that its back coating is disposed against said front coatingof the lowermost sheet, whereby upon application of pressure to thestack, said back coating of the middle sheet and the front coating ofthe initially lowermost sheet are forced together to bring the first andsecond components of the first reaction system into said reactivecontact to thereby produce a colored mark, said sheets being capable ofrearrangement such that said initially lowermost sheet overlies saidinitially uppermost sheet with the front coating of the initiallylowermost sheet disposed against the back coating of the initiallyuppermost sheet, whereby upon application of pressure to the stack, saidfront coating of the initially lowermost sheet and the back coating ofthe initially uppermost sheet are forced together to bring the first andsecond components of the second reaction system into said reactivecontact to thereby produce another colored mark.
 2. A manifold set asset forth in claim 1 wherein a coating of at least one of said sheetscomprises a plurality of pressure rupturable microcapsules containing acolor forming reactive component thereof, said microcapsules beingrupturable upon application of said pressure to said stack.
 3. Amanifold set as set forth in claim 1 wherein each of said firstcomponents are contained in a plurality of pressure rupturablemicrocapsules which form a portion of each corresponding coating.
 4. Amanifold set of carbonless recording sheets comprising:a stack includingat least three superimposed sheets; each of said sheets having front andback coatings thereon; the coatings of the initially uppermost sheeteach comprising, as a reactive component thereof, a first reactivecomponent of a first initially colorless forming reaction system, thecoatings of the middle sheet each comprising, as reactive componentsthereof, a second reactive component of said first reaction system and afirst reactive component of a second initially colorless color formingreaction system, the coatings of said initially lowermost sheet eachcomprising, as a reactive component thereof, a second reactive componentof said second reaction system, said first and second components of thefirst reaction system being capable of interreacting to produce acolored mark upon coming into reactive contact, said first and secondcomponents of the second reaction system likewise being capable ofinterreacting to produce a colored mark upon coming into reactivecontact, said first component of the first system and said secondcomponent of the second system being incapable of interreacting toproduce a colored mark, said first component of the second system andsaid second component of the first system being incapable ofinterreacting to produce a colored mark, said sheets being initiallydisposed with said uppermost sheet overlying said middle sheet and withthe latter overlying the lowermost sheet in such manner that the backcoating of the uppermost sheet is disposed against the front coating ofthe middle sheet and the back coating of the latter is disposed againstthe front coating of the lowermost sheet, whereby, upon application ofpressure to the stack, said back coating of the uppermost sheet and thefront coating of the middle sheet are forced together to bring the firstand second components of the first reaction system into said reactivecontact to thereby produce a colored mark, and said back coating of themiddle sheet and the front coating of the lowermost sheet are likewiseforced together to bring the first and second components of the secondreaction system into said reactive contact to thereby simultaneouslyproduce a second colored mark,said sheets being capable of rearrangementsuch that the front coating of the uppermost sheet is disposed againstthe back coating of the middle sheet and the front coating of the latteris disposed against the back coating of the lowermost sheet, wherebyupon application of pressure to the stack, said front coating of theuppermost sheet and the back coating of the middle sheet are forcedtogether to bring the first and second components of the first reactionsystem into said reactive contact to thereby produce another coloredmark, and said front coating of the middle sheet and the back coating ofthe lowermost sheet are likewise forced together to bring the first andsecond components of the second reaction system into said reactivecontact to thereby simultaneously produce another second colored mark.5. A manifold set as set forth in claim 4 wherein a coating of at leastone of said sheets comprises a plurality of pressure rupturablemicrocapsules containing a color forming reactive component thereof,said microcapsules being rupturable upon application of said pressure tosaid stack.
 6. A manifold set as set forth in claim 4 wherein each ofsaid first components are contained in a plurality of pressurerupturable microcapsules which form a portion of each correspondingcoating.
 7. A sheet for use in connection with a manifolded set ofcarbonless forms wherein at least two initially colorless reactionsystems are utilized, wherein each of said systems comprises separateinitially colorless first and second reactive components which arereactable when brought into reactive contact with one another to producea colored mark and wherein the first component of each of said systemsis incapable of reacting with the second component of any of the othersystems to produce a colored mark, said sheet comprising:a substratelayer; and a coating on said layer, said coating comprising an admixtureof the first component of one of said systems and the second componentof another of said systems.
 8. A manifold set as set forth in claim 7wherein each of said first components are contained in a plurality ofpressure rupturable microcapsules which form a portion of eachcorresponding coating.